TWI462537B - Communication apparatus and radio frequency equalizer - Google Patents

Description

Communication device and radio frequency equalizer

The present invention relates to a radio frequency equalizer, and more particularly to a radio frequency equalizer that can compensate for the power flatness of a radio frequency signal.

Due to advances in mobile communication systems in recent years, it has been able to provide a variety of communication services, such as voice services, data services, and video services, without being restricted to the user's location. The general mobile communication system is a multiple access system, which means that multiple users can access the system and configure appropriate wireless network resources to the user at the same time, and the multiple access technologies used include: global action Global System for Mobile communications (GSM), Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), and Long Term Evolution (Long Term) Evolution, LTE) technology and more. In addition, Advanced Long Term Evolution (LTE Advanced) is an enhanced version of the technology developed in accordance with the Long Term Evolution (LTE) standard.

In order to enable a mobile communication device to support a variety of different communication technologies (for example, GSM, CDMA, WCDMA, LTE, etc.), the design of multi-modal mobile communication devices has gradually become the mainstream of the market. Since the frequency bands used by various communication technologies are not the same, multi-modal mobile communication devices must support a sufficiently wide frequency band, for example, extending from 0.7 gigahertz (GHz) to 3 gigahertz (GHz).

However, due to the characteristics of the electronic components in the mobile communication device, under the same input power, the processed communication device may not have the same output power for the radio frequency signals of different frequency bands, and the power of the radio frequency signal is not Flat phenomenon. Figure 1a shows a plot of RF signal output power versus frequency, which is an example of RF signal output power decreasing with increasing frequency. Figure 1b shows another curve of the output power of the RF signal relative to the frequency. This is an example of the increase in the output power of the RF signal as the frequency increases. The power increment and decrement are both ones of the uneven output power of the RF signal. .

In order to solve the phenomenon that the output power of the radio frequency signal is not flat, the present invention proposes an RF equalizer, which can effectively compensate the output power flatness of the radio frequency signal.

According to an embodiment of the invention, a communication device includes a radio frequency transceiver, a radio frequency equalizer, a power amplifier, and a duplexer. The radio frequency transceiver is configured to generate a plurality of radio frequency signals according to the complex fundamental frequency signals. The RF equalizer is coupled to the RF transceiver for receiving the RF signal, and generates a plurality of equalized RF signals according to a control signal, wherein a frequency response corresponding to the RF equalizer is adjusted according to the control signal. The power amplifier is coupled to the RF equalizer for receiving the equalized RF signal and amplifying the equalized RF signal to generate a plurality of amplified RF signals. The duplexer is coupled to the power amplifier for receiving the amplified RF signal and transmitting the amplified RF signal to an antenna.

According to another embodiment of the present invention, a radio frequency equalizer is configured to receive a plurality of radio frequency signals, and generate a plurality of equalized radio frequency signals according to a control signal, including a first resistor, a second resistor, a first capacitor, and a first An inductor, a first switch, a second switch, a second capacitor, a second inductor, and a third switch. The first resistor is coupled to an input. The second resistor is coupled between the first resistor and an output. The first switch is coupled to the input end, the first capacitor and the first inductor, and is configured to selectively couple the first capacitor or the first inductor to the input end according to the control signal. The second switch is coupled to the output end, the first capacitor and the first inductor for selectively coupling the first capacitor or the first inductor to the output end according to the control signal. The third switch is coupled to the first resistor, the second resistor, the second capacitor, and the second inductor, and is configured to selectively couple the second capacitor or the second inductor to the first resistor and the second resistor according to the control signal point.

In order to make the manufacturing, operating methods, objects and advantages of the present invention more apparent, the following detailed description of the preferred embodiments and the accompanying drawings

Example:

Figure 2 is a block diagram showing a communication device in accordance with an embodiment of the present invention. The communication device 200 can include at least a baseband signal processing device 210, a radio frequency transceiver 220, a radio frequency equalizer 230, a power amplifier 240, a directional coupler 250, a duplexer 260, and an antenna 270. The baseband signal processing device 210 is configured to process and generate a baseband signal. The baseband signal processing device 210 may include a plurality of hardware devices to perform baseband signal processing, including analog to digital conversion (ADC)/digital to analog conversion (DAC), gain adjustment. , modulation and demodulation, and encoding/decoding. The baseband signal processing device 210 may further include one of transmitting an uplink signal, TX, and one of receiving a downlink signal, RX.

The radio frequency transceiver 220 is configured to process the radio frequency signal, which can receive the radio frequency signal of the downlink, and convert the radio frequency signal into a baseband signal for further processing by the baseband signal processing device 210, or received from the baseband signal processing device 210. The baseband signal of the uplink and the baseband signal is converted into a radio frequency signal for transmission. The radio frequency transceiver 220 can also include a plurality of hardware devices to perform the above radio frequency conversion. For example, the radio frequency transceiver 220 can include a mixer for multiplying the baseband signal by the mobile communication system. One of the transmission frequencies used, where the transmission frequency can be 900 MHz, 1800 MHz or 1900 MHz used by GSM, or 900 MHz, 1900 MHz, or 2100 MHz used by UMTS, or 900 MHz, 2100 used by LTE. Megahertz, or 2600 MHz, or depending on other radio access technology standards.

The RF equalizer 230 is coupled to the RF transceiver 220 for receiving an uplink RF signal and generating an equalized RF signal according to a control signal Ctrl and the received uplink RF signal. According to an embodiment of the present invention, the control signal Ctrl is generated by the power detector 280 for adjusting a frequency response corresponding to the RF equalizer 230, so that the communication device 200 can compensate the RF signal through the RF equalizer 230. The output power is not flat (the following paragraphs will be described in more detail with respect to the RF equalizer 230 proposed by the present invention).

The power amplifier 240 is coupled to the RF equalizer 230 for receiving the equalized RF signal and amplifying the equalized RF signal to generate an amplified RF signal. The directional coupler 250 is coupled between the power amplifier 240 and the duplexer 260 for transmitting most of the amplified RF signal to the duplexer 260, and feeding back a part of the amplified RF signal to the power detector. 280. The directional coupler 250 can include an input 耦 coupled to one of the outputs of the power amplifier 240, coupled to one of the inputs of the duplexer 250, an output 埠, coupled to the load 290 (typically a 50 ohm load) One of the signal isolation ports is used to feedback one of the amplified RF signals.

The duplexer 260 is coupled to the power amplifier 240 through the directional coupler 250 for receiving the amplified RF signal and transmitting the amplified RF signal to the antenna 270. The amplified RF signal is finally transmitted to the air through the antenna. In downlink signal processing, duplexer 260 receives the downlink radio frequency signal from antenna 270 and transmits the received signal to receive 埠RX of radio frequency transceiver 220.

According to an embodiment of the invention, the power detector 280 is configured to detect the power of the amplified RF signal and generate a control signal Ctrl according to the power of the amplified RF signal. It should be noted that the power detector 280 can be implemented as a stand-alone device or integrated into the radio frequency transceiver 220 as shown in FIG. 2, and the present invention is not limited to any of the embodiments. In addition, when the power detector 280 is integrated into the RF transceiver 220, the power detector 280 can also be a standalone device or can be implemented by components (eg, a processor) internal to the RF transceiver 220. The invention is not limited to any one embodiment.

According to another embodiment of the invention, the power detector can also be integrated into the baseband signal processing device. Figure 3 is a block diagram showing a communication device according to another embodiment of the present invention. The communication device 300 can include at least a baseband signal processing device 310, a radio frequency transceiver 320, a radio frequency equalizer 230, a power amplifier 240, a directional coupler 250, a duplexer 260, and an antenna 270. The introduction of the baseband signal processing device 310, the radio frequency transceiver 320, the radio frequency equalizer 230, the power amplifier 240, the directional coupler 250, the duplexer 260, and the antenna 270 can be referred to the related description of FIG. 2, and Let me repeat.

In this embodiment, the power detector 380 is integrated into the baseband signal processing device 310. The power detector 380 can also be a standalone device or can be implemented by components (e.g., a processor) within the baseband signal processing device 310. The invention is not limited to any embodiment. It should be noted that, in this embodiment, a part of the amplified RF signal that is returned by the directional coupler 250 can be directly transmitted to the power detector 380 for power detection, or firstly frequency-reduced by the RF transceiver 320. The conversion is then transmitted to the power detector 380 for power detection, and the present invention is not limited to any of the embodiments.

According to an embodiment of the invention, the power detector 280/380 is mainly used for detecting the flatness of the power of the amplified RF signal with respect to one of the frequencies. For example, the power detector 280/380 can record radio frequency signals of different frequency bands (eg, different transmission bands used by different communication technologies, or different transmission bands used by the same communication technology, or others) via the power amplifier 240. The power is then sized to obtain a plot of the power of the amplified RF signal versus frequency (eg, the curves shown in Figures 1a and 1b). After obtaining the power versus frequency curve, the power detector 280/380 can further determine whether the power of the amplified RF signal is incremented or decremented as the frequency increases according to the curve to generate a corresponding control signal Ctrl to adjust the RF. The frequency response of the equalizer 230.

Figure 4 is a circuit diagram showing a radio frequency equalizer according to an embodiment of the present invention. The RF equalizer 430 can include resistors R1 and R2, capacitors C1 and C2, inductors L1 and L2, and switches S1, S2, and S3. The resistors R1 and R2 are coupled in series between the input terminal IN and the output terminal OUT of the RF equalizer 430. The switch S1 is coupled between the input terminal IN of the RF equalizer 430 and the capacitor C1 and the inductor L1 for selectively coupling one of the capacitor C1 or the inductor L1 to the input terminal IN according to the control signal Ctrl. The switch S2 is coupled between the output terminal OUT of the RF equalizer 430 and the capacitor C1 and the inductor L1 for selectively coupling one of the capacitor C1 or the inductor L1 to the output terminal OUT according to the control signal Ctrl. Therefore, in response to the different states of the control signal Ctrl, one of the capacitor C1 and the inductor L1 will be coupled in parallel with the resistors R1 and R2 between the input terminal IN and the output terminal OUT. Similarly, the switch S3 is coupled between the resistors R1 and R2 and between the capacitor C2 and the inductor L2 for selectively coupling the capacitor C2 or the inductor L2 to the connection point N1 of the resistors R1 and R2 according to the control signal Ctrl.

According to an embodiment of the present invention, when the power detector 280/380 determines that the power of the amplified RF signal decreases as the frequency increases (for example, as shown by the graph of FIG. 1a), the first state can be generated ( For example, a control signal Ctrl of a logic high level state or a logic low level state is used to control the switching operation of the switches S1, S2 and S3, thereby obtaining an equivalent circuit diagram of the RF equalizer as shown in FIG. 5a.

As shown in FIG. 5a, when the control signal Ctrl has the first state, the equivalent circuit of the RF equalizer 530 includes resistors R1 and R2, a capacitor C1 and an inductor L2. The capacitor C1 and the resistors R1 and R2 are coupled in parallel between the input terminal IN and the output terminal OUT, and the inductor L2 is coupled between the connection point N1 of the resistors R1 and R2 and an end point (for example, a ground point). It is worth noting that the inductor L1 is electrically insulated from the input terminal IN and the output terminal OUT, and the capacitor C2 is electrically insulated from the resistors R1 and R2.

Figure 5b is a graph showing a frequency response curve of a radio frequency equalizer according to an embodiment of the present invention. The frequency response curve shown in Fig. 5b is the frequency response curve corresponding to the equivalent circuit of the RF equalizer shown in Fig. 5a. As shown in the figure, the frequency response corresponding to the equivalent circuit of the RF equalizer 530 is a curve in which the insertion loss decreases as the frequency of the RF signal increases. Therefore, when the power detector 280/380 detects the amplification. When the power of the RF signal decreases as the frequency increases, the control signal Ctrl can be set to have a first state for compensating for the uneven output power of the RF signal through the RF equalizer 230.

It is worth noting that the capacitance value of the capacitor C1 and the inductance value of the inductor L2 can be adjusted according to the slope of the required frequency response to achieve the best compensation effect. According to an embodiment of the invention, when the capacitance value of the capacitor C1 and the inductance value of the inductor L2 are smaller, the slope of one of the frequency responses corresponding to the RF equalizer is larger. For example, as shown in FIG. 5b, the capacitance value of the capacitor C1 corresponding to the frequency response curve 502 and the inductance value of the inductor L2 are smaller than the capacitance value of the capacitor C1 corresponding to the frequency response curve 501 and the inductance value of the inductor L2.

According to another embodiment of the present invention, when the power detector 280/380 determines that the power of the amplified RF signal is increasing as the frequency increases (for example, as shown by the graph of FIG. 1b), the second state may be generated. The control signal Ctrl (for example, a logic low level state or a logic high level state) is used to control the switching operations of the switches S1, S2 and S3, thereby obtaining an equivalent circuit diagram of the RF equalizer as shown in FIG. 6a. .

As shown in FIG. 6a, when the control signal Ctrl has the second state, the equivalent circuit of the RF equalizer 630 includes resistors R1 and R2, a capacitor C2, and an inductor L1. The inductor L1 and the resistors R1 and R2 are coupled in parallel between the input terminal IN and the output terminal OUT, and the capacitor C2 is coupled between the connection point N1 of the resistors R1 and R2 and an end point (for example, a ground point). It should be noted that at this time, the capacitor C1 is electrically insulated from the input terminal IN and the output terminal OUT, and the inductor L2 is electrically insulated from the resistors R1 and R2.

Figure 6b is a graph showing a frequency response curve of a radio frequency equalizer according to another embodiment of the present invention. The frequency response curve shown in Figure 6b is the frequency response corresponding to the equivalent circuit of the RF equalizer shown in Figure 6a. As shown in the figure, the frequency response corresponding to the equivalent circuit of the RF equalizer 630 is a curve in which the insertion loss increases as the frequency of the RF signal increases. Therefore, when the power detector 280/380 detects the amplification. When the power of the RF signal increases as the frequency increases, the control signal Ctrl can be set to have a second state for compensating for the uneven output power of the RF signal through the RF equalizer 230.

It is worth noting that the capacitance value of the capacitor C2 and the inductance value of the inductor L1 can be adjusted according to the slope of the required frequency response to achieve the best compensation effect. According to an embodiment of the present invention, when the capacitance value of the capacitor C2 and the inductance value of the inductor L1 are larger, the slope of one of the frequency responses corresponding to the radio frequency equalizer is larger. For example, as shown in FIG. 6b, the capacitance value of the capacitor C2 corresponding to the frequency response curve 602 and the inductance value of the inductor L1 are greater than the capacitance value of the capacitor C2 corresponding to the frequency response curve 601 and the inductance value of the inductor L1.

Figure 7 is a graph showing the power versus frequency of an amplified RF signal output by a power amplifier, compensated by a radio frequency equalizer, in accordance with an embodiment of the present invention. As shown in the figure, in the embodiment of the present invention, the frequency response corresponding to the RF equalizer is adjusted by the control signal Ctrl, so that the power of the amplified RF signal is relative to The flatness of the frequency curve can be effectively increased, thus solving the phenomenon that the output power of the radio frequency signal is not flat.

The use of ordinal numbers such as "first," "second," or "third," as used in the <Desc/Clms Page number>> The order of the steps, and only used as an identifier to distinguish different elements having the same name (with different ordinal numbers).

The present invention has been described above with reference to the preferred embodiments thereof, and is not intended to limit the scope of the present invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

200, 300. . . Communication device

210, 310. . . Base frequency signal processing device

220, 320. . . RF transceiver

230, 430, 530, 630. . . RF equalizer

240. . . Power amplifier

250. . . Directional coupler

260. . . Diplexer

270. . . antenna

280, 380. . . Power detector

290. . . load

501, 502, 601, 602. . . curve

C1, C2. . . capacitance

Ctrl. . . control signal

IN. . . Input

L1, L2. . . inductance

N1. . . Junction

OUT. . . Output

R1, R2. . . resistance

RX. . . Receiving 埠

S1, S2, S3. . . switch

TX. . . Transfer

Figure 1a shows a plot of RF signal output power versus frequency.

Figure 1b shows another plot of RF signal output power versus frequency.

Figure 2 is a block diagram showing a communication device in accordance with an embodiment of the present invention.

Figure 3 is a block diagram showing a communication device according to another embodiment of the present invention.

Figure 4 is a circuit diagram showing a radio frequency equalizer according to an embodiment of the present invention.

Figure 5a is an equivalent circuit diagram showing a radio frequency equalizer according to an embodiment of the present invention when the control signal has a first state.

Figure 5b is a graph showing a frequency response curve of a radio frequency equalizer according to an embodiment of the present invention.

Figure 6a is an equivalent circuit diagram showing a radio frequency equalizer according to an embodiment of the present invention when the control signal has a second state.

Figure 6b is a graph showing a frequency response curve of a radio frequency equalizer according to another embodiment of the present invention.

Figure 7 is a graph showing the power versus frequency of an amplified RF signal output by a power amplifier after being compensated by a radio frequency equalizer according to an embodiment of the invention.

430. . . RF equalizer

C1, C2. . . capacitance

Ctrl. . . control signal

IN. . . Input

L1, L2. . . inductance

N1. . . Junction

OUT. . . Output

R1, R2. . . resistance

S1, S2, S3. . . switch

Claims (14)

A communication device includes: a radio frequency transceiver for generating a plurality of radio frequency signals according to a plurality of baseband signals; a radio frequency equalizer coupled to the radio frequency transceiver for receiving the radio frequency signals, and according to a control signal Generating a plurality of equalized RF signals; a power amplifier coupled to the RF equalizer for receiving the equalized RF signals, and amplifying the equalized RF signals to generate a plurality of amplified RF signals An RF signal; a duplexer coupled to the power amplifier for receiving the amplified RF signals, and transmitting the amplified RF signals to an antenna; a power detector for detecting a power of the amplified RF signal, and generating the control signal according to the power of the amplified RF signal; and a directional coupler coupled between the power amplifier and the duplexer for using a portion The amplified RF signals are fed back to the power detector, wherein a frequency response corresponding to the RF equalizer is adjusted according to the control signal. The communication device of claim 1, wherein the power detector is included in the radio frequency transceiver. The communication device of claim 1, further comprising: a baseband signal processing device for processing and generating the baseband signals, wherein the power detector is included in the baseband signal processing device. The communication device of claim 1, wherein the RF equalizer comprises: a first resistor coupled to an input terminal; and a second resistor coupled to the first resistor and an output terminal a first capacitor; a first switch coupled to the input terminal, the first capacitor and the first inductor for selectively selecting the first capacitor or the first according to the control signal An inductor is coupled to the input terminal; a second switch coupled to the output terminal, the first capacitor and the first inductor for selectively coupling the first capacitor or the first inductor according to the control signal Connected to the output terminal; a second capacitor; a second inductor; and a third switch coupled to the first resistor, the second resistor, the second capacitor, and the second inductor for controlling The signal selectively couples the second capacitor or the second inductor to a connection point of the first resistor and the second resistor. The communication device of claim 4, wherein when the capacitance value of one of the first capacitors and the inductance value of the second inductor are smaller, a slope of the frequency response corresponding to the RF equalizer is more Big. The communication device of claim 4, wherein a slope of the frequency response corresponding to the RF equalizer is greater when the inductance value of one of the first inductors and the capacitance value of the second capacitor are larger The bigger. The communication device of claim 1, wherein the The power detector detects that the power of the amplified RF signal decreases as the frequency of the amplified RF signal increases. The RF equalizer has an equivalent circuit including: a first resistor coupled a second resistor coupled between the first resistor and an output; a capacitor coupled between the input and the output; and an inductor coupled to the first A resistor is connected between the connection point and an end point of one of the second resistors. The communication device of claim 1, wherein the power detector detects that the power of the amplified RF signal increases as the frequency of the amplified RF signal increases. The equalizer has an equivalent circuit comprising: a first resistor coupled to an input; a second resistor coupled between the first resistor and an output; an inductor coupled to the input And a capacitor coupled between the first resistor and one of the second resistors and an end point. The communication device of claim 1, wherein the power detector generates the control signal to adjust the frequency response corresponding to the RF equalizer to increase the power of the amplified RF signals. The flatness of the curve of one of the frequencies of the amplified RF signals. An RF equalizer for receiving a plurality of RF signals, and generating a plurality of equalized RF signals according to a control signal, comprising: a first resistor coupled to an input terminal; and a second resistor coupled to the RF resistor Between the first resistor and an output; a first capacitor; a first switch coupled to the input terminal, the first capacitor and the first inductor for selectively selecting the first capacitor or the first inductor according to the control signal The first switch is coupled to the output terminal, the first capacitor and the first inductor, and is configured to selectively couple the first capacitor or the first inductor to the control signal according to the control signal The output terminal; a second capacitor; a second inductor; and a third switch coupled to the first resistor, the second resistor, the second capacitor, and the second inductor for selecting according to the control signal The second capacitor or the second inductor is coupled to a connection point of the first resistor and the second resistor. The radio frequency equalizer of claim 10, wherein when the control signal has a first state, the first capacitor is coupled between the input end and the output end, the first inductor and the The input end and the output end are electrically insulated, the second inductor is coupled between the connection point and the end point of the first resistor and the second resistor, and the second capacitor and the first resistor and the second The resistor is electrically insulated. The radio frequency equalizer of claim 10, wherein when the control signal has a second state, the first inductor is coupled between the input end and the output end, the first capacitor and the The input end and the output end are electrically insulated, and the second capacitor is coupled between the connection point of the first resistor and the second resistor and an end point, and the second inductor and the first resistor and The second resistor is electrically insulated. The radio frequency equalizer according to claim 10, wherein one of the frequency responses of the RF equalizer is one when the capacitance value of one of the first capacitors is smaller than the inductance value of the second inductor The slope is larger. The radio frequency equalizer according to claim 10, wherein when the inductance value of one of the first inductors and the capacitance value of one of the second capacitors are larger, a frequency response corresponding to the radio frequency equalizer is The greater the slope.